When posting photos or videos of oversized carry-ons, include the airline and airport, as well as the hashtag #CarryonShame

Photo: Screen Capture, Twitter

When posting photos or videos of oversized carry-ons, include the...

When posting photos or videos of oversized carry-ons, include the... Photo-6404999.87245 - SFGate

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Most overhead compartments are 15 inches tall, large enough to set regulation carry-on bags on their sides. This bag, which is supposed to be just 9 inches deep, filled the space (and had to be forced in to fit), making it at least 6 inches deeper than allowed.

In an attempt to keep passengers happy, Virgin America has a more liberal standard for "carry-on" luggage, adding a few inches onto each dimension.

Photo: Spud Hilton, Bad Latitude

In an attempt to keep passengers happy, Virgin America has a more...

In an attempt to keep passengers happy, Virgin America has a more... Photo-6405003.87245 - SFGate

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Brand new bag out of the box. The tag says it's carry-on compliant and is 9 inches deep, expandable to 11 inches. Yet, with nothing in it and not expanded, it's already 11 inches. Whether intentionally or not, the manufacturer is selling bags that are the wrong size.

Photo: Spud Hilton, Bad Latitude

Brand new bag out of the box. The tag says it's carry-on compliant...

Brand new bag out of the box. The tag says it's carry-on... Photo-6405004.87245 - SFGate

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Several manufacturers make bags that come with a removable daypack. Without the daypack, the bag is regulation carry-on size, but with it, the rolling bag needs to be checked.

Photo: Spud Hilton, Bad Latitude

Several manufacturers make bags that come with a removable daypack....

Several manufacturers make bags that come with a removable daypack.... Photo-6405005.87245 - SFGate

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During the past year, United has begun cracking down on passengers attempting to bring clearly oversized luggage on board and, instead of gate-checking the bag, United workers have sent passengers back through security to check a bag (and pay for it) at the check-in counter.

Photo: Spud Hilton, Bad Latitude

During the past year, United has begun cracking down on passengers...

During the past year, United has begun cracking down on passengers... Photo-6405006.87245 - SFGate

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Recently, United has gone so far as to include a page in the electronic check-in that requires passengers to confirm that they understand the dimensions of carry-on bags.

Photo: Spud Hilton, Bad Latitude

Recently, United has gone so far as to include a page in the...

Recently, United has gone so far as to include a page in the... Photo-6405007.87245 - SFGate

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In general, because they often have more items of value in them, gate-checked bags are far more likely to have property missing at the end of the flight.

Photo: Spud Hilton, Bad Latitude

In general, because they often have more items of value in them,...

In general, because they often have more items of value in them,... Photo-6405008.87245 - SFGate